JERUSALEM
— One after another, Palestinian officials Wednesday sought to distance their cause from a deadly attack against a US diplomatic convoy in the Gaza Strip, urging the US not to react precipitously.

The blast - which killed three Americans and injured another - was the most significant direct attack on a US target since Israelis and Palestinians resumed outright warfare against each other three years ago.

Palestinian Authority President Yasser Arafat denounced the attack as "an ugly crime." The PA's caretaker prime minister, Ahmed Qureia, said that "we strongly condemn this incident and we will ... find the source of this attack." Two militant groups denied involvement in the bombing.

The bomb was apparently a remote-controlled device planted along a main road that leads away from the major crossing point between Israel and the Gaza Strip. The convoy was ferrying US officials who planned to interview Palestinian candidates applying for Fulbright scholarships.

At about the same time as Palestinian officials were calling for a thorough investigation, two major Palestinian militant groups - Hamas and Islamic Jihad - denied responsibility. Hamas, in particular, has claimed responsibility for roadside bombs that have destroyed Israeli tanks. Wednesday's bomb may not have been that powerful, but it dug a car-sized crater in the sandy Gazan soil and mangled the armored vehicle that took the brunt of the explosion.

Denials aside, the anti-American anger of Palestinians is hard to miss. Palestinian youths from a nearby refugee camp threw stones at US investigators as they arrived at the blast scene Wednesday. And one analyst was willing to say that the attack may reflect Palestinian frustration with the Bush administration's strong support for Israel and its on-again-off-again approach toward Middle East peacemaking.

"If this [attack] was done by Palestinians it would be a reply to the stubbornness of this administration and especially this last veto," says Palestinian political analyst Hani Masri, referring to the US decision this week to squelch a UN Security Council resolution. The resolution condemning Israel's construction of a barrier in the West Bank intended to separate Israelis and Palestinians. The barrier, which has drawn high-level US criticism, has been denounced internationally because its route effectively annexes some Palestinian lands.

It seems unlikely that those behind the roadside bomb acted only in response to the veto, since the attack appeared well-planned, but there seems little doubt that they intentionally targeted US officials. US convoys - usually consisting of two or three armored SUVs, often marked with diplomatic license plates and accompanied by local security forces - are a routine sight and easy to spot. The vehicle destroyed in Wednesday's blast bore license plates identifying it as American.

The Bush administration has often changed course in dealing with the Israeli-Palestinian conflict. At first US officials said Mr. Bush and his top advisers were determined not to repeat the perceived mistakes of President Clinton, who spent the final weeks of his presidency in an intensive and unsuccessful effort to broker an Israeli-Palestinian peace deal.

Nonetheless the level of Israeli-Palestinian violence has drawn the Americans into the efforts to mediate the conflict, since they alone are seen as having sufficient leverage to disentangle the two parties.

The attacks of Sept. 11, 2001 and the ensuing "war on terrorism," have made it more difficult for the US to countenance any dealings with Mr. Arafat - whose condemnations of political violence against Israelis have sometimes seemed halfhearted - but the US nonetheless proceeded with an attempt to implement a "road map" toward peace early this summer.

That effort has lost steam and the Bush administration has lately sounded resigned to supporting its main ally - Israel - without expending much diplomatic capital in trying to make peace. Traditionally, peace efforts have lagged as US presidential elections have drawn close.

If Palestinian dismay at this situation has turned to attack, it's hard to imagine just what the motive would be, except to reinforce the status quo. As one Western official says, speaking on condition of anonymity, "Whoever wants the US out and backing [Israeli Prime Minister Ariel] Sharon, this is all they had to do."

Attacks against US officials have occurred in other Middle Eastern countries, including Lebanon, Saudi Arabia, and Iraq. But Palestinian militant groups have said they have no interest in attacking non-Israeli targets. "Islamic Jihad has no intention to extend a cycle of confrontation with any nation ... except the occupation. Our battle is with the occupiers only," Nafez Nazzam, a spokesman for the Palestinian militant group told Associated Press Wednesday.

For the most part, Palestinian leaders find themselves in a quandary in dealing with the US. While they recognize that Americans represent the only force capable of pressuring Israel to comply with a peace deal, they resent what they perceive as the US government's pro-Israeli bias.

It seems inconceivable to many Palestinians that the US can criticize Israel's barrier, for example, and not support a UN resolution on the subject. "The American position on the Middle East problem is not balanced," says Hatem Abdel Khader, a member of the Palestinian parliament. "But we consider that America is important for the peace process. If America does not succeed and Bush does not succeed, who will?"